Fixing devices for securing a wheel to a structure are known. Thus, for example, bicycle wheels, motorcycle wheels, trike wheels and wheels of karts, prams and the like are known to be secured by a wide variety of types of fixing devices. In the field of bicycles and motorcycles it is known to secure a wheel to a set of forks of the vehicle. A typical set of forks comprises a pair of spaced apart fork legs although in general there must be at least one fork leg. A fork is thus a structural member that is configured for affixing a wheel axle thereto. Typically for a two wheeled bicycle there is a set of front forks that comprises two fork legs to which is affixed a front wheel and there is also a pair of rear fork legs (commonly known in the art as stays) for affixing a rear wheel. The portion of the fork where the wheel is fixed thereto comprises a dropout. By a dropout it is meant a wheel mounting point, typically located at an end portion of the fork, that comprises an aperture in which a fixing may be located or applied so as to secure the wheel axle to the fork. However the term is also commonly used to also mean the aperture itself and the term is used interchangeably herein, the exact meaning being dependent upon the particular context in question as will be understood by those skilled in the art. The pair of front forks are spaced apart as are the pair of rear wheel stays. Typical dropouts have inner sides or faces (i.e. faces which face each other), outer sides that are opposite the other sides, and an orifice. A common type of dropout orifice is in the form of an elongate aperture to provide a slot for receiving a wheel axle. The dropouts of more conventional bicycles comprise slots that are located at the ends of the forks and which have an opening for receiving the axle from a direction that is more or less defined by the longitudinal axis of an associated fork leg. Such slotted dropouts enable the wheel axle to be removed from the dropouts in a direction away from the lower ends of the dropouts and these are commonly referred to in the art as open bore dropouts. It is known to secure a wheel in such open bore wheel mounting points by using an axle that is permanently fixed within a wheel hub and which comprises screw threaded end portions for affixing a threaded nut thereto, the hub being located between the inner faces of the mounting points. A first nut locates against an outer face of one of the mounting points and a second nut locates against the outer face of the second. This known type of system requires use of a tool such as a spanner to release the nuts and is thus time consuming.
Improved wheel clamping devices have been devised, which are known as “quick release” (QR) wheel clamping devices. As regards open bore type dropouts, by the term “quick release” it is meant a fixing that can be readily undone according to its intended (or primary) mode of operation by a person using only their hands and without the need to use a tool to achieve this. A lever mechanism (or other QR means) may be provided which is operable by hand so as to apply or disengage the fixing. By intended mode, in the case of a QR lever mechanism, it is meant achieving the required release of the fixing by using the lever as opposed to dismantling the fixing in some other way. In the case of quick release clamping of hub/axle assemblies in open bore dropouts it is known to be able to provide a clamping arrangement such that a lever is provided to apply (or remove) a tensional force to (or from) a spindle that passes inside the axle, the force applied effectively acting to pull the two fork legs in a direction towards one another so as to clamp them to the hub/axle assembly. A good example is disclosed in the French patent application having publication no. FR2782471. Although FR2782471 discloses a quick release wheel hub assembly it may be considered to be unnecessarily complicated in that the bearings are located in the forks rather than in the wheel hub assembly. A problem with the system disclosed in FR2782471 is that it is highly desirable to use commonly available wheels and wheel hub assemblies wherein the wheel hub itself comprises the bearings, U.S. Pat. No. 5,165,762 also discloses a form of quick release apparatus that comprises a hub having a spindle passing therethrough and to which there is attached a cam lever at a first end and an end cap located at the other end. Following positioning of the end portions of the spindle within each respective dropout the end cap is then positioned next to a first dropout and the cam lever is then used to clamp the apparatus to the forks. In normal operation of quick release wheel clamping devices of the type designed for use with open bore dropouts the axle remains intact with the hub that comprises the bearings when the wheel is removed from the forks. This is because the open bore dropouts simply allow the axle fixing to be lowered away from the dropouts when the fixing is loosened sufficiently.
Open bore dropouts are suitable for many types of bicycles and motorcycles. However the rigidity of the wheel mounting and assembly is known to be less than optimal. Increased rigidity is required in certain types of cycling/motorcycling activities where high tensional and compressional forces are applied to the vehicle. Thus in the field of mountain biking and also in the field of BMX cycling it is desired to improve the rigidity of the wheel mounting system of a given vehicle. To improve rigidity the width of the dropouts may be increased. By width it is meant the distance from the inner side (or face) to the outer side of the dropout, this being a distance measured in a direction parallel to the wheel axle. U.S. Pat. No. 6,386,643 (Marzocchi) discloses a quick releasable hub assembly of increased rigidity in that it comprises dropouts that are substantially wider than on typical cycle forks. This reference also discloses a quick-release clamping mechanism of the known hub/spindle mechanism described above. Although U.S. Pat. No. 6,386,643 provides improved rigidity, the fact that the dropouts are of the open bore type results in less than optimal rigidity as regards the securement of the wheel hub to the forks of the vehicle.
In applications such as mountain biking it is highly desirable to use dropouts that are fully or substantially closed bore. By fully closed bore it is meant a wheel mounting orifice that has a circumference of 360° at all times. However use of such fully closed bore dropouts means that the above mentioned quick release assemblies, as exemplified by U.S. Pat. No. 6,386,643, are not able to be inserted into the dropouts without substantially dismantling the axle assembly and thus losing the intended quick release effect of the quick release assembly.
A known assembly for creating a closed bore type of arrangement as used with a “quick release” hub of the type exemplified above is schematically illustrated in FIGS. 1 and 2. The system schematically illustrated in FIGS. 1 and 2 is substantially based on the fork and hub assembly disclosed in U.S. Pat. No. 6,386,643. FIGS. 1 and 2 schematically illustrate a pair of spaced apart front forks 101 and 102 each comprising respective end wheel mounting portions 103 and 104. The extended width of the dropouts is, for example, indicated for fork leg 102 between points 105 and 106 (i.e. corresponding to the approximate diameter of the axle), the extended width providing improved rigidity as compared with narrower fork dropouts that are found on more conventional bicycles. A quick release axle (as designed for use with open bore dropouts) 107 comprises a first end having a cam lever 108 and a second end comprising an end cap 109. The axle 107 is insertable in dropouts 103, 104 generally in the direction indicated by arrow 110. Following insertion in the dropouts the end cap 109 and cam lever 108 are used to cause a tensional force to be applied across the main body of the elongate axle 111 to secure the axle to the dropouts. However to improve rigidity and to secure the axle in the dropouts it is known to close the open bores of the forks. Thus as shown in FIGS. 1 and 2 a pair of plates are known to be attached to the ends of the respective dropouts, these being plates 112 and 113. Plates 112 and 113 are respectively secured to the lower ends of the dropouts by respective bolts 114 and 115. By closing the open ended dropouts using plates 112 and 113 the rigidity and the securement of the axle as held in the dropouts is improved and this is particularly desirable in mountain biking wherein cornering and maneuvering of wheels over rocks and the like causes great stresses to be put on the forks and, in particular, on the front forks. The front forks are in fact known to move relative to each other and the closed bore helps to ensure that the axle does not move within the dropouts and therefore it helps to ensure that the forks do not move relative to each other. A problem with the fork/axle assembly schematically illustrated in FIGS. 1 and 2 is that it is difficult and time consuming to remove and replace the axle from/to the open bore dropouts in view of the need to respectively remove and replace the plates. Also the person riding the particular vehicle is required to carry specific tools to effect tightening or loosening of the small bolts 114 and 115 in the event that a wheel is being respectively fitted or removed. A further problem is that frequently the bolts or plates may be lost or damaged during removal of a wheel or insertion of a wheel into the fork dropouts. Open bore dropouts configured to be closed when in use may be suitably referred to as semi-permanent closed bore dropouts in that they are not closed at all times.
In view of the problems associated with the fork/axle assembly schematically illustrated in FIGS. 1 and 2 it is desirable to provide an improved axle/fork assembly that benefits from use of closed bore dropouts. Unlike traditional bicycles, axles used in sports such as mountain biking may have a greater diameter, again for purposes of providing greater rigidity and strength of the axle/fork assembly. Typically such higher rigidity axles are greater than 9 mm in diameter and in general they are at least 20 mm in diameter. Thus the axle main body 111 schematically illustrated in FIGS. 1 and 2 is 20 mm in diameter as is common in mounting the front wheels of mountain bikes. In order to hold an axle rigidly in one or more dropouts it is highly desirable to use closed bore dropouts, the most rigid system comprising dropouts that are fully closed bore in that the dropout orifices simply comprise holes having a full 360° circumference. A fully closed bore dropout thus does not comprise a slit which would render the orifice as not encircling the axle by a full 360°. By making use of fully closed bore dropouts or near closed bore dropouts (that is dropouts which substantially encircle the axle, but which comprise a gap in the wall of the dropout orifice, the gap constituting less than 180° of angular measure around the circumference of the axle) effectively means that the axle cannot be inserted in the dropouts in the usual manner. The term “substantially closed bore” is used hereinafter to refer to fully closed bore dropouts and/or near closed bore dropouts. A property of such substantially closed bore dropouts is that the axle must, at least during normal placement or removal of the axle assembly to be from the substantially closed bore, be inserted in a direction substantially parallel to the longitudinal axis that is defined by the axle when in position in the dropout(s). This is in contrast to the usual method of inserting an axle in open bore dropouts wherein, as described earlier, the axle is inserted in a direction that is transverse to the in-use position of the longitudinal axis of the axle when in position in the dropouts. Without disassembling the QR spindle system for this type of fork/axle assembly (thereby removing the spindle) it is simply not possible to fit the QR axle in to the dropouts.
Other improved high rigidity axle/fork assemblies are known, such as, for example, those retailed by the US company in the name of Rockshox Incorporated of California. One such system marketed by Rockshox is that known as the “Tullio 20 mm QR system”. The Tullio system comprises a large diameter axle that is located within a pair of fork dropouts that are substantially closed bore (each dropout orifice comprises a narrow gap thereby rendering the bore as not strictly fully closed bore, but near closed bore). The gap is provided so that a cam lever located on the exterior surface of a fork dropout can be closed thereby forcing the edges of the slit towards each other and thereby ensuring that the axle is held rigidly in each of the fork dropouts. In this system the cam levers are mounted on the fork dropouts and not on the actual axle assembly.
Rockshox Inc. have also developed a further 20 mm QR system which incorporates a cam lever on the axle assembly (rather than on a fork) and which is used to effect expansion of a member within the axle portion of the axle assembly, the expansion thereby ensuring that an end portion of the axle is held tightly within the dropout. In this single cam lever system a first end of the axle assembly is first screwed into one of the fork dropouts and once the first end of the axle is firmly in place, the second end comprising the cam lever is used to effect expansion of the expansion member to thereby secure both first and second ends within their respective dropouts. Unlike the system schematically illustrated in FIGS. 1 and 2 the two aforementioned Rockshox systems are configured such that the axle itself is removed from a given wheel hub through which it passes, this being necessary by virtue of either a substantially or a completely closed bore constraint of the forks/stays for which the system is configured to be used. Removal of the axle is in a direction parallel to the longitudinal axis of the axle when the axle is in its operational position in the hub.
In relation to clamping assemblies configured for use with substantially closed bore dropouts the requirements for an assembly to qualify as “quick release” are therefore that:                (a) it does not require use of a special tool, such as a spanner i.e. it is readily operated, in its normal intended mode of operation, by hand; and        (b) in its normal mode of operation it is configured to enable an axle portion of the clamping assembly to be inserted through and removed from a substantially closed bore dropout in the direction of the longitudinal axis of the axle.        
Although an open bore dropout QR system of the type discussed earlier could be dismantled and then fitted through a closed bore dropout system it would be time consuming and there is the risk of loss of and/or damage to the separated components. Such dismantling of a system would not be operated as primarily intended (to quickly remove a wheel from a structure to which the wheel is attached) and is thus not considered to constitute a quick release mechanism in relation to such closed bore use.
In contrast to the axle/fork assemblies of the types described above, the axle is releasably mounted in or through a given hub to which a wheel is attached. In these latter types of axle assemblies the large diameter axle is placed in or withdrawn from the hub in a direction that is parallel to the longitudinal axis of the axle. During operation within a given hub the axle locates against one or more sealed bearings of the type in the form of a ring (usually two, one at each end of the hub). Sealed bearings of this type comprise a so-called outer race and an inner race between which there is provided a series of bearings. For the bearing to work correctly the inner race must be stationary relative to the axle. The outer race is configured to move relative to the inner race during hub movement. To prevent the inner race from moving relative to the axle a force is applied longitudinally (that is in the direction of the longitudinal axis of the axle) by virtue of the hub and axle configuration itself. The force on the inner race is provided by slightly raised portions within the hub/axle assembly—these are configured to communicate with the inner race and they translate a force to the inner race by virtue of the clamping effect provided by the way in which the hub and axle are held with respect to each other. The small raised portions (typically in the form of a lip) stop the inner race from moving relative to the axle.
In the aforementioned single cam Rockshox system a force is supplied to ensure that the inner race is stationery relative to the main axle portion of the assembly. This force is provided by a raised portion on the axle itself. As a separate action, the Rockshox assembly holds the fork legs by virtue of the expansion of a member in the axle when this member is positioned within the confines of the orifice of the closed bore dropout.
A problem associated with both of the aforementioned Rockshox systems is that, although the axle assembly is fixed to the dropouts, the rigidity of these systems is considered to be less than optimal. It is therefore desired to provide an alternative assembly for rigidly mounting a high rigidity axle in highly rigid front or rear fork systems whilst retaining the ability to remove or replace a wheel using a quick release mechanism. Not only is an alternative required, but the systems designed by Rockshox are considered to be somewhat less than optimal in that the clamping effect of the quick release cams is configured to provide a force on the axle in the direction defined by a radius extending between a point on the circumference of the axle and a point on the longitudinal axis located along the length of and at the centre of the axle. Clamping in this way means that the axle is only prevented from moving (relative to the fork or forks to which it is attached) in the longitudinal direction by virtue of the magnitude of the force applied by (a) the two cam levers (in the Tullio assembly) or (b) by the single lever in the single cam lever Rockshox system. In the sport of mountain biking high forces (especially as regards front fork systems) may potentially cause the axle in these systems to move, particularly if the cam or cams are not tightened sufficiently or if they become loosened in some way during operation of the bike. There is thus a need to provide an alternative high rigidity closed bore axle/fork assembly system that can be removed without the need for a tool to be used and which is designed so as to be removed easily and quickly.
Increasing the rigidity and strength is highly desirable in the wheel axle mountings of vehicles such as mountain bikes. For this reason closed bore dropouts have been used in conjunction with a wider diameter axle that can be secured within the closed bore dropouts. Use of closed bore dropouts is particularly desirable in bicycles with suspension forks of the type that are common on mountain bikes. Use of suspension forks can create unbalanced compressional and tensional forces in the fork legs during cornering and manoeuvering of the bicycle. This is particularly so in the case of a set of front forks which are configured to hold a wheel of the vehicle that is used for steering the vehicle. The known methods for securing larger diameter axles, commonly 20 mm in diameter, differ in design, but each suffers from either requiring specialist tools for the removal of the wheel and/or requires an excessive number of operations to be completed before the wheel can be removed by virtue of the axle being displaced longitudinally through closed-bore dropouts rather than simply being dropped out as is the case with open-bore dropouts.